阅读说明：本技术 钢铁表面激光熔覆陶瓷增强Ni基复合涂层及其制备方法 (Steel surface laser cladding ceramic reinforced Ni-based composite coating and preparation method thereof ) 是由 于慧君 赵龙杰 陈传忠 于 2019-10-18 设计创作，主要内容包括：本发明公开了一种钢铁表面激光熔覆陶瓷增强Ni基复合涂层及其制备方法。陶瓷增强Ni基复合涂层,由陶瓷相和Ni60A的混合粉末在钢试件表面经激光熔覆制得,混合粉末中,陶瓷相为ZrN、ZrB<Sub>2</Sub>或ZrC,其质量分数为5～45wt.％,余量为Ni60A。激光功率为3～5kW,扫描速度为200～400mm/min,光斑直径为3～4mm,预置粉末厚度为0.5～1.5mm,氩气流量为5～15L/min,搭接率为30％～50％。Ni60A+ZrN涂层具有高的耐磨性,在激光功率3kW,扫描速度300mm/min的条件下,Ni60A+10wt.％ZrN涂层的耐磨性提高到基材的9.67倍。在激光功率3kW,扫描速度300mm/min的条件下,Ni60A+30wt.％ZrB<Sub>2</Sub>涂层的耐磨性提高到基材的4.14倍。(The invention discloses a ceramic reinforced Ni-based composite coating for steel surface laser cladding and a preparation method thereof. The ceramic reinforced Ni-based composite coating is prepared by laser cladding of mixed powder of ceramic phase and Ni60A on the surface of a steel test piece, wherein the ceramic phase is ZrN and ZrB 2 Or ZrC, the mass fraction of which is 5-45 wt.%, and the balance Ni 60A. The laser power is 3-5 kW, the scanning speed is 200-400 mm/min, the spot diameter is 3-4 mm, the thickness of the preset powder is 0.5-1.5 mm, the argon flow is 5-15L/min, and the lap joint rate is 30-50%. The Ni60A + ZrN coating has high wear resistance, and the wear resistance of the Ni60A +10 wt.% ZrN coating is improved to 9.67 times that of the base material under the conditions that the laser power is 3kW and the scanning speed is 300 mm/min. Ni60A +30 wt.% ZrB at a laser power of 3kW and a scanning speed of 300mm/min 2 The abrasion resistance of the coating is improved to 4.14 times that of the base material.)

1. A ceramic reinforced Ni-based composite coating for steel surface laser cladding is characterized in that: prepared by laser cladding of mixed powder of ceramic phase and Ni-based powder on the surface of a steel test piece, wherein in the mixed powder, the ceramic phase is ZrN or ZrB₂The mass fraction is 5-45 wt.%, and the balance is Ni-based powder.

2. The steel surface laser cladding ceramic reinforced Ni-based composite coating of claim 1, characterized in that: the zirconium nitride powder accounts for 5-25 percent, and the balance is Ni 60A;

further, the content of the zirconium nitride powder is 5% -15%, and the balance is Ni 60A;

further, the content of the zirconium nitride powder was 10%, and the balance was Ni 60A.

3. The steel surface laser cladding ceramic reinforced Ni-based composite coating of claim 1, characterized in that: the content of zirconium boride powder is 25-45%, and the balance is Ni 60A;

further, the content of zirconium boride powder is 25-35%, and the balance is Ni 60A;

further, the content of zirconium boride powder was 30%, and the balance was Ni 60A.

4. The steel surface laser cladding ceramic reinforced Ni-based composite coating of claim 1, characterized in that: the base material is structural steel, tool steel, special performance steel or cast iron;

further, the base material is structural steel;

further, the base material is 45 steel.

5. A preparation method of a ceramic reinforced Ni-based composite coating by laser cladding on the surface of steel is characterized by comprising the following steps: the method comprises the following steps: and cleaning the surface of the matrix material, pre-paving the mixed powder on the surface, and carrying out laser cladding on the matrix material to obtain the laser cladding coating.

6. The preparation method of the ceramic-reinforced Ni-based composite coating for steel surface laser cladding according to claim 5, characterized in that: the laser power is 3-5 kW, the scanning speed is 200-400 mm/min, the diameter of a light spot is 3-4 mm, the lap joint rate is 30-50%, the argon flow is 5-15L/min, and the thickness of the preset powder is 0.5-1.5 mm.

7. The preparation method of the ceramic-reinforced Ni-based composite coating for steel surface laser cladding according to claim 6, characterized in that: when the ceramic material is zirconium nitride, the laser power is 3kW, the scanning speed is 300mm/min, the spot diameter is 3.5mm, the overlapping rate is 35%, the argon flow is 12L/min, and the thickness of the preset powder is 1 mm.

8. The preparation method of the ceramic-reinforced Ni-based composite coating for steel surface laser cladding according to claim 6, characterized in that: when the ceramic material is zirconium boride, the laser power is 3kW, the scanning speed is 300mm/min, the spot diameter is 4mm, the lap joint rate is 30%, the argon flow is 10L/min, and the thickness of the preset powder is 1.2 mm.

9. The Ni-based composite coating prepared by the preparation method of the steel surface laser cladding ceramic reinforced Ni-based composite coating according to any one of claims 5 to 8.

10. A friction part characterized by: the coating is the Ni-based composite coating described in any one of claims 1 to 4 and claim 9;

furthermore, the base material is structural steel, tool steel, special performance steel or cast iron;

furthermore, the base material is structural steel;

still further, the base material is No. 45 steel.

Technical Field

The invention particularly relates to a ceramic reinforced Ni-based composite coating for steel surface laser cladding and a preparation method thereof.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

45 steel is common medium carbon structural steel, has higher strength and good cutting performance, and is widely used for manufacturing connecting rods, bolts, gears, shaft parts and the like. However, in a severe service environment, 45 steel parts are susceptible to wear and corrosion, resulting in failure and economic loss. The protective coating is prepared by utilizing a surface modification technology, so that the wear resistance and corrosion resistance of the part can be effectively improved, and the service life of the part is prolonged.

Laser cladding is a surface modification technology which utilizes a laser beam with high energy density to scan a cladding material, so that the cladding material and a small part of base material are rapidly melted and solidified together to obtain a metallurgical bonding coating. As a novel surface modification technology, compared with the traditional method, the laser cladding technology has the advantages of small heat input, low dilution rate, large coating thickness, high bonding strength, high cladding speed, fine tissue and the like. At present, the laser cladding technology has been widely paid attention to and researched in the fields of mechanical manufacturing, petrochemical industry, aerospace and the like, and has a good application prospect.

The source of the laser cladding material is wide, and the reasonable selection of the cladding material is the key for obtaining ideal service performance. Commonly used alloy materials for laser cladding are 3 series of powders of Ni-based, Co-based and Fe-based. Among them, the Ni-based alloy has high wear resistance, corrosion resistance, high-temperature oxidation resistance, good wettability and moderate price, and is widely applied. The Ni-based self-fluxing alloy powder mainly contains alloy elements such as Cr, B, Si, C, Fe and the like. Cr and Fe can be dissolved in gamma-Ni in a solid mode to cause solid solution strengthening, and can be combined with B and C to generate a plurality of hard phases to cause second phase strengthening and dispersion strengthening, so that the hardness and the wear resistance of the alloy are improved. Ni and Cr can form a dense oxide film, causing passivation, thereby enhancing the corrosion resistance and high temperature oxidation resistance of the alloy. B and Si can reduce the melting point of the alloy, improve the fluidity of the melt, and react with O element to generate borate and silicate, thereby playing roles in deoxidation and slagging. At present, the laser cladding technology widely uses Ni-based self-fluxing alloy powder as a cladding material to prepare wear-resistant and corrosion-resistant coatings on the surfaces of parts such as rollers, cams, plungers, conveying rollers of rolling mills and the like. However, the alloy coating can not meet the use requirements in the face of severe service environments such as large load, high stress, high speed, strong corrosion and the like.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention aims to provide a ceramic reinforced Ni-based composite coating for steel surface laser cladding and a preparation method thereof.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a ceramic-reinforced Ni-base composite coating for the surface of steel is prepared from the mixture of ceramic phase (ZrN or ZrB) and Ni-base powder through laser cladding₂The mass fraction is 5-45 wt.%, and the balance is Ni-based powder.

In order to improve the wear resistance and corrosion resistance of the steel surface, the inventors conducted a series of tests including adding ZrN and ZrB of different proportions to Ni-based alloy powder, respectively₂Or ZrC and other ceramic powder, and performing laser cladding on the surface of the steel to prepare the ceramic-reinforced Ni-based composite coating. Test results show that the three series of cladding materials have certain improvement effect on the wear resistance of steel, wherein the Ni60A + ZrN coating has lower microhardness, and the Ni60A + ZrB coating has lower microhardness₂The micro-hardness of the coating is high, and the micro-hardness of the Ni60A + ZrC coating is intermediate.

Generally, on the premise that the friction coefficient of the surface of the cladding layer is equivalent, the hardness of the cladding layer is higher, and the wear resistance of the cladding layer is better. The inventors have found that when the mass fraction of ZrN in the ZrN/Ni 60A mixed powder is about 10 wt.%, the abrasion resistance of the cladding layer can be nearly 10 times that of the steel matrix when the laser power is about 3kW and the scanning speed is about 300mm/min, and an unexpected technical effect is obtained. ZrB₂The wear resistance of the cladding layer of Ni60A can be improved by about 4 times, while the wear resistance of the cladding layer of ZrC and Ni60A can be improved by only about 2 times.

The inventors have further tested that ZrN and Ni60A tend to grow into a regular octahedron shape surrounded by (111) planes during laser cladding when the percentage of ZrN is around 10 wt.%. In addition, it can be seen that a part of eutectic structures are attached to the ZrN crystal growth, which is beneficial to increase the bonding strength between phases and inhibit the second phase from falling off in the abrasion environment. The Ni-based solid solution dendrite is used as a matrix, so that stress concentration can be relieved, and the toughness of the coating is improved. Fine eutectic structures are filled among the dendrites, and grain boundary strengthening is realized. The hard ZrN is embedded on the matrix and has the function of strengthening the second phase. The synergistic effect of the two obviously improves the wear resistance of the cladding layer.

When the addition of ZrN is increased, the residual stress and brittleness of the coating are increased, the possibility of crack initiation is increased, cracks are continuously developed and connected with each other in the abrasion process, so that the material is peeled off, and the abrasion resistance of the coating is reduced. On the other hand, excessive ZrN reduces the toughness of the material surface, the ceramic phase can be brittle under the action of normal load and friction force, and fragments enter between friction pairs to cause abrasive wear. Therefore, when the amount of ZrN added is too large, the wear resistance of the coating layer is lowered.

When ZrB₂When the percentage content of (B) is about 30 wt.%, ZrB₂And ZrB added externally during the laser cladding process of Ni60A₂Remain in the coating layer and perform the functions of second phase strengthening and dispersion strengthening. At the same time, ZrB₂There are partial decomposition conditions which lead to the occurrence of ZrC, ZrB in the coating₁₂And (4) phases. In addition, the Ni60A powder contains 16.55 wt.% of Cr element, and thus the coating contains CrB and Cr₂₃C₆Cr, these borides or carbides having high hardness, with ZrB₂And the like play a role in strengthening the structure together, so that the wear resistance of the coating is improved.

The preparation method of the ceramic-reinforced Ni-based composite coating for laser cladding on the surface of steel comprises the following steps: cleaning the surface of the steel test piece to remove oxide skin; spreading mixed powder of a ceramic phase and Ni60A on a surface to be fused and strickling; and (3) placing the steel sample in an argon environment, and carrying out laser cladding to obtain the composite coating.

In some embodiments, the Ni-based powder is Ni 60A.

In some embodiments, the cladding process parameters of the Ni60A + ZrN coating are: the laser power is 3-5 kW, and the scanning speed is 200-400 mm/min. The diameter of a light spot is 3-4 mm, the lap joint rate is 30-50%, the argon flow is 5-15L/min, and the thickness of the preset powder is 0.5-1.5 mm.

Further, the cladding technological parameters of the Ni60A + ZrN coating are as follows: the laser power is 3kW, and the scanning speed is 300 mm/min. The diameter of a light spot is 3.5mm, the lap joint rate is 35%, the argon flow is 12L/min, and the thickness of the preset powder is 1 mm.

In some embodiments, Ni60A + ZrB₂The cladding technological parameters of the coating are as follows: the laser power is 3-5 kW, and the scanning speed is 200-400 mm/min. The diameter of a light spot is 3-4 mm, the lap joint rate is 30-50%, the argon flow is 5-15L/min, and the thickness of the preset powder is 0.5-1.5 mm.

Further, Ni60A + ZrB₂The cladding technological parameters of the coating are as follows: the laser power is 3kW, and the scanning speed is 300 mm/min. The diameter of a light spot is 4mm, the lap joint rate is 30%, the argon flow is 10L/min, and the thickness of the preset powder is 1.2 mm.

In some embodiments, ZrN is 5-45 wt.%, with the balance being Ni 60A. The particle size of the ZrN powder is-200 meshes. The particle size of the Ni60A powder is + 325-140 meshes.

Further, the mass fraction of ZrN is 5-25 wt.%, and the balance is Ni 60A.

Furthermore, the content of the zirconium nitride powder is 5 to 15 percent, and the balance is Ni 60A;

still further, ZrN was 10 wt.%, with the balance Ni 60A. In Ni60A + ZrN series coatings, the coating cladding quality of the mixture ratio is optimal, and the main phases comprise gamma- (Ni, Fe), ZrN and Cr₂B、Cr₂₃C₆And Fe₃And N, the coating has good toughness and highest wear resistance.

In some embodiments, ZrB₂The mass fraction of (a) is 5-45 wt.%, and the balance is Ni 60A. ZrB₂The particle size of the powder was-200 mesh. The particle size of the Ni60A powder is + 325-140 meshes.

Go toStep (b) of (ZrB)₂The mass fraction of (A) is 25-45%, and the balance is Ni 60A.

Furthermore, the content of the zirconium boride powder is 25-35 percent, and the balance is Ni 60A;

still further, ZrB ₂30 wt.%, the balance Ni 60A. Ni60A + ZrB₂In the series of coatings, the coating with the proportion comprises ZrB₂、CrB、Fe₂B、Cr₂₃C₆、ZrC、ZrB₁₂The equal hard phase has the best combination of hardness and toughness and the highest wear resistance.

The working surface of the steel test piece is processed with the Ni-based composite coating.

The invention has the beneficial effects that:

by adding ZrN or ZrB into the cladding material₂ZrN or ZrB is prepared by laser cladding₂A reinforced Ni-based composite coating. The ceramic phase is added as a hard phase to reinforce the coating structure, so that the hardness and the wear resistance of the coating are obviously improved.

In the Ni60A + ZrN coating, Ni-based solid solution dendrite is used as a matrix, so that stress concentration can be relieved, and the toughness of the coating is improved. Fine eutectic structures are filled among the dendrites, and grain boundary strengthening is realized. The hard ZrN is embedded on the matrix phase and plays a role in strengthening the second phase. ZrN. In addition, a part of eutectic structures are attached to the growth of ZrN crystals, so that the bonding strength between phases of the materials is increased, and the falling of ZrN in a wear environment is inhibited. Therefore, the Ni60A + ZrN coating has high wear resistance. The wear resistance of the Ni60A +10 wt.% ZrN coating increased to 9.67 times that of the substrate at a laser power of 3kW and a scanning speed of 300 mm/min.

Ni60A+ZrB₂In the coating, the toughness of the gamma- (Ni, Fe) matrix phase is good, and the crack tendency of the coating can be reduced. Additional ZrB₂Remains in the coating structure and has the effects of second-phase strengthening and dispersion strengthening. In addition, the coating also comprises CrB and Fe₂B、Cr₂₃C₆、ZrC、ZrB₁₂Equal hard phases, these hard phases and ZrB₂The wear resistance of the coating is further improved by the synergistic effect. At laser power of 3kW, sweepNi60A +30 wt.% ZrB at a drawing speed of 300mm/min₂The abrasion resistance of the coating is improved to 4.14 times that of the base material.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.

Fig. 1 shows cladding quality of Ni60A +15 wt.% ZrN coating under different process conditions in example 1 of the present invention;

FIG. 2 shows the cladding quality of Ni60A + ZrN coating (3kW, 300mm/min) with different ZrN addition amounts in example 1 of the invention;

FIG. 3 shows Ni60A +15 wt.% ZrB under different process conditions in example 2 of the present invention₂Cladding quality of the coating;

FIG. 4 shows different ZrBs in example 2 of the present invention₂Addition amount of Ni60A + ZrB₂Cladding quality of the coating (3kW, 300 mm/min);

FIG. 5 shows the cladding quality of Ni60A +15 wt.% ZrC coating under different process conditions of comparative example of the present invention;

FIG. 6 shows the cladding quality of Ni60A + ZrC coating (3kW, 300mm/min) with different ZrC addition amount of the comparative example of the invention;

FIG. 7 is an X-ray diffraction pattern of a laser clad Ni60A +15 wt.% ZrN coating (4kW, 250mm/min) coating of example 1 of the present invention;

FIG. 8 is a drawing of laser cladding Ni60A +15 wt.% ZrB in example 2 of the invention₂X-ray diffraction spectrum of the coating (4kW, 250 mm/min);

FIG. 9 is an X-ray diffraction spectrum of a comparative example of the present invention laser clad Ni60A +15 wt.% ZrC (4kW, 250mm/min) coating;

FIG. 10 is a structural morphology of a Ni60A +15 wt.% ZrN coating (5kW, 150mm/min) laser clad according to example 1 of the present invention;

FIG. 11 is a microstructure of a laser cladding Ni60A +15 wt.% ZrN coating according to example 1 of the present invention, (a, b)5kW, 250 mm/min; (c, d)5kW, 350 mm/min;

FIG. 12 is a drawing of laser cladding Ni60A +10 wt.% ZrB in example 2 of the invention₂Coating (4kW, 250mm/min)) The microstructure morphology of (a);

FIG. 13 is a laser cladding of Ni60A +20 wt.% ZrB in example 2 of the invention₂Microstructure morphology of the coating (4kW, 250 mm/min);

FIG. 14 is a microstructure morphology of a comparative example of the present invention laser cladding a Ni60A +15 wt.% ZrC coating (5kW, 250 mm/min);

FIG. 15 is a microstructure morphology of a comparative example of the present invention laser cladding a Ni60A +15 wt.% ZrC coating (5kW, 150 mm/min);

FIG. 16 is a microstructure morphology of a comparative example of the present invention laser cladding a Ni60A +15 wt.% ZrC coating (5kW, 350 mm/min);

FIG. 17 shows the wear loss of the laser cladding Ni60A + ZrN coating (3kW, 300mm/min) and the base material in example 1 of the present invention;

FIG. 18 is a drawing of laser cladding Ni60A + ZrB in example 2 of the present invention₂Abrasion loss of the coating (3kW, 300mm/min) and the substrate.

FIG. 19 shows the wear loss of a laser clad Ni60A + ZrC coating (3kW, 300mm/min) and a substrate according to a comparative example of the present invention.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

ZrN is an interstitial phase with a density of 7.32g/cm³Face centered cubic B1-NaCl type structure, Fm-3m space group, lattice parameter a 0.45783 nm. Because 1 Zr atom forms strong ionic bond with 6 surrounding N atomsZrN has high melting point (2950 ℃), high microhardness (19.6 +/-0.4 GPa) and high elastic modulus (510 GPa). Meanwhile, ZrN has good corrosion resistance and high temperature resistance. Therefore, ZrN is a more ideal reinforcing phase and can play a role in improving the performance of the coating.

ZrB₂Is an interstitial compound, and the crystal structure of the interstitial compound is C32-AlB of a hexagonal system₂Type P6/mmm space group, lattice parameter a 0.3169nm, c 0.3530 nm. 12B atoms surround 1 Zr atom, an ionic bond is formed between Zr-B, and a covalent bond is formed between B-B. Thus, ZrB₂Has high melting point (3425 ℃), high hardness (2000HV), good wear resistance and corrosion resistance, and can be used as an effective reinforcing phase for preparing the metal ceramic composite coating.

ZrC density is 6.74g/cm³The crystal is of a face-centered cubic B1-NaCl type structure, Fm-3m space group and has a lattice constant a of 0.46930 nm. 1 Zr atom is combined with 6C atoms around the Zr atom by ionic bonds to form a negative ion coordination octahedron. Because the Zr-C ionic bond energy distributed symmetrically is high and is difficult to break, ZrC has high melting point (3530 ℃), high hardness (2890HV) and good chemical stability. When ZrC exists in the microstructure as an interstitial phase, the sliding of dislocation can be hindered, and the grain boundary and the subboundary are enhanced, so that the strength, the wear resistance and the high-temperature creep resistance of the material are improved. ZrC is used as an additional ceramic phase to prepare the ZrC enhanced Ni-based composite coating, so that the wear resistance of the coating can be improved.

In the invention, an appropriate amount of ZrN and ZrB is added into Ni60A powder₂And ZrC, and the ceramic reinforced Ni-based composite coating is prepared on the steel substrate by laser cladding with a preset method, combines the advantageous properties of the Ni-based alloy and the ceramic phase, improves the wear resistance of the substrate, and has good protective effect on the substrate.

Test materials used

Ni-based self-fluxing alloy powder (Ni60A) with a particle size of-140 to +325 mesh and a bulk density of 4.24g/cm³The flowability was 17.66s/50 g.

The particle size of the ZrN powder is-200 meshes, and the purity is more than or equal to 99 percent. ZrB₂The powder has a particle size of-200 meshes and a purity of more than or equal to 99% of the total weight of the composition. The grain size of the ZrC powder is-200 meshes, and the purity is more than or equal to 99 percent.